Cryopreservation of Potato Shoot Tips for Long-Term Storage

Abstract

Cryopreservation is currently the only method which allows long-term conservation of living clonal plant material in the vapor or liquid phase of nitrogen (at −140 to −196 °C) allowing tissue to be viable for decades or perhaps centuries. Specifically, for species with recalcitrant seeds or requiring constant vegetative propagation, it is the method of choice for the long-term conservation of its genetic resources. The protocol described here is a modification of a previously developed plant vitrification solution 2 (PVS2)—droplet vitrification method of potato shoot tips, adapted from Musa species. Utilizing this protocol, the International Potato Center (CIP) has successfully stored in the cryobank more than 3000 cultivated potato accessions, belonging to seven species and nine different taxa [16], originating principally from ten countries in South and Central America. As part of CIP’s quality management system, all vegetative material placed in cryo is routinely subsampled, thawed, and assessed to confirm that whole plantlets can be produced after storage in liquid nitrogen. Complete plant recovery rates of thawed shoot tips range from 20% to 100% (average rate: 60%). This chapter describes the complete set of steps from the routine procedure of cryopreserving potato shoot tips for long-term conservation.

Overcoming Challenges for Shoot Tip Cryopreservation of Root and Tuber Crops

“…Cryopreservation procedures have already been established and implemented for many vegetatively propagated crops, including most RTCs [38]. Cryopreservation techniques for RTCs have been developed using pollen, seeds, shoot tips, and cell suspensions as a plant source [54][55][56][57][58]. The propagule choice to be cryopreserved depends on whether the seed is orthodox, whether in vitro/cryopreservation protocols are already developed, and on whether the genes or the specific genetic combination of elite germplasm are the program conservation targets [59].…”

The world’s largest potato cryobank at the International Potato Center (CIP) – Status quo, protocol improvement through large-scale experiments and long-term viability monitoring

“…Large cryopreserved plant genetic resources collections, have been established in only a small number of organizations around the world, e.g. the National Center for Genetic Resources Preservation (US, Fort Collins, CO), International Musa Germplasm Transit Centre (Europe, Belgium, Leuven), Leibniz Institute of Plant Genetics and Crop Plant Research (IPK, Europe, Germany, Gatersleben), International Potato Center (South America, Peru, Lima), National Institute of Agrobiological Sciences (Asia, Japan, Tsukuba), and National Agrobiodiversity Center (Asia, South Korea, Suwon) [ Jenderek and Reed, 2017 ; Panis et al., 2020 ; Vollmer et al., 2021 ; Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 2022 ]. The second-largest potato cryobank after CIP is located at IPK (1845 accessions).…”

“…A set of 73 diverse potato landraces ( Table 1 ) selected from the CIP genebank were cryopreserved with the above-described routine cryopreservation protocol ( Vollmer et al., 2021 ). After thawing, shoot tips were placed on culture media with four different sucrose concentrations (0.07 M, 0.1 M, 0.2 M, and 0.3 M), in the dark, for nine days before they were transferred to culture medium with the standard sucrose concentration (0.07 M).…”

“…Cryopreservation is defined as the conservation of biological material at ultra-low temperatures, generally in the liquid (-196°C) or vapor phase of liquid nitrogen (LN) and is considered a cost- and space-efficient long-term conservation method for clonal crops ( Vollmer et al., 2021 ). “Cryopreserved plant materials can theoretically remain alive for centuries, after which they can be removed from the frozen conditions and regenerated into healthy, growing plants” ( Food and Agriculture Organization (FAO), 2021 ).…”

In Vitro Technology in Plant Conservation: Relevance to Biocultural Diversity

“…Nardostachys jatamansi medicinal micropropagation * Himalayan region [156] Sequoiadendron giganteum ornamental meristem culture Sierra Nevada, USA [157] Artocarpus altilis medicinal, food meristem culture *ˆPacific Islands [158] Solanum tuberosum food, ceremonial nodal explant tissue culture *ŝ hoot tip, micro tuber cryopreservation Global distribution [159][160][161][162] Hordeum vulgare food embryo cryopreservation * SW Asia, Himalayas [163] Ceiba pentandra medicinal, wood apical shoot culture Tropical forests, global distribution [164] Zea mays food, ceremonial embryo, seed cryopreservation Global distribution [165,166] * Indicates in vitro methods have been documented for conservation purposes. ˆDenotes in vitro projects carried out in explicit collaboration with Indigenous Peoples; unmarked reports do not disclose this information.…”